A Tale of Two Interglacials: A Stalagmite Stable Isotope Record of Climate inYucatán, Mexico Since 128,000 YBP

Earth’s glacial climate has been punctuated with warm interglacial periods lasting ~10,000 years. Current anthropogenic greenhouse gas forcing is pushing climate towards a state that deviates from established Quaternary patterns. In predicting future rapid climate changes, two key analogs are the end of the last glacial, Termination 1 at ~14,000 years ago, and the Eemian, the penultimate interglacial ~130-114,000 years ago. Speleothems or cave formations record changes in the isotopic composition of rainwater infiltrating the cave during paleoclimate shifts. Stalagmite YAX-2 was deposited in Yucatán, Mexico within a -40m deep cave lacking natural entrances from ~128,000 years ago to the most recent millennium, therefore including both analogs. U/Th dating shows that YAX-2 grew most rapidly during interglacials. We present the YAX-2 record of stable carbon and oxygen isotope values as indicators of environmental change in Yucatán, Mexico and compare our results to published research on abrupt tropical climate change and interglacial climate dynamics.